Research On Inherent Sensitivity Of Erbium-doped Fiber Laser To Magnetic Force

Optical fiber sensors have become the core of sensor research in recent years due totheir advantages of small size,light weight,and high integration.Sensing is an extremely important part in medical,security,aerospace and defense fields.High-performance sensors have become the goals pursued by many researchers.Birefringence is a very important physical parameter in an optical fiber,and birefringence has a very significant effect on the external physical effects on the optical fiber such as pressure and temperature.In this paper,the effect of magnetic field force on birefringence in erbium-doped fiber is studied.The main contents of this paper are: First,a brief summary of magnetic field sensors in recent years,including electrical magnetic field sensors and optical magnetic field sensors,and the basic principles of optical fiber sensing are described.The magnetism of the material and the magnetization of the material in the magnetic field are discussed in detail.The formula of the magnetic field force is deduced,and several different magnetic field effects are briefly introduced.In the next step,the working principle and preparation method of the core orthogonal dual-frequency fiber laser of the sensing system are introduced,and the theoretical model of birefringence in the fiber is introduced,and the basic method of birefringence research is proposed.Secondly,the internal magnetic field force of the optical fiber is analyzed.Depending on the position of the optical fiber and the magnetic field and the structure of the experimental equipment,the birefringence in the optical fiber is affected by the magnetic field force to some extent to calculate and predict.In the experimental part,different experiments were designed based on the formula of the magnetic field force in the experimental structure.The beat frequency of the output laser of the Erbium-doped dual-polarization fiber laser in the spatial gradient magnetic field and the uniform magnetic field was recorded and analyzed,and observed.The response above 500 MHz,and the response will be more obvious in the case of increasing the magnetic field gradient,and the experimental conclusion that accords with the theoretical calculation is obtained.Finally,under the dynamic gradient magnetic field,the degree of response to the magnetic field force inside the optical fiber has been studied.